U.S. patent application number 16/576471 was filed with the patent office on 2020-01-09 for safety power disconnection for power distribution over power conductors to power consuming devices.
The applicant listed for this patent is Corning Optical Communications LLC. Invention is credited to Ami Hazani.
Application Number | 20200014196 16/576471 |
Document ID | / |
Family ID | 62002190 |
Filed Date | 2020-01-09 |
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United States Patent
Application |
20200014196 |
Kind Code |
A1 |
Hazani; Ami |
January 9, 2020 |
SAFETY POWER DISCONNECTION FOR POWER DISTRIBUTION OVER POWER
CONDUCTORS TO POWER CONSUMING DEVICES
Abstract
Safety power disconnection for remote power distribution in
power distribution systems is disclosed. The power distribution
system includes one or more power distribution circuits each
configured to remotely distribute power from a power source over
current carrying power conductors to remote units to provide power
for remote unit operations. A remote unit is configured to decouple
power from the power conductors thereby disconnecting the load of
the remote unit from the power distribution system. A current
measurement circuit in the power distribution system measures
current flowing on the power conductors and provides a current
measurement to the controller circuit. The controller circuit is
configured to disconnect the power source from the power conductors
for safety reasons in response to detecting a current from the
power source in excess of a threshold current level indicating a
load.
Inventors: |
Hazani; Ami; (Ra'anana,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Corning Optical Communications LLC |
Charlotte |
NC |
US |
|
|
Family ID: |
62002190 |
Appl. No.: |
16/576471 |
Filed: |
September 19, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/IL2018/050368 |
Mar 29, 2018 |
|
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16576471 |
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62479656 |
Mar 31, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02D 70/1222 20180101;
Y02D 70/144 20180101; H02J 13/00 20130101; H04B 10/25753 20130101;
H02J 13/0062 20130101; H04Q 2213/08 20130101; Y02D 70/10 20180101;
Y02D 70/142 20180101; Y02D 70/166 20180101; H02J 13/0003 20130101;
H02J 13/00017 20200101; H04B 2210/08 20130101; G01R 31/08 20130101;
H02J 13/0004 20200101; Y02D 70/00 20180101; Y02D 70/122 20180101;
G01R 19/16571 20130101; H02H 7/263 20130101; Y02D 70/164 20180101;
H02H 7/261 20130101; H04B 10/808 20130101; H02J 13/00016 20200101;
H04W 88/085 20130101; H04B 10/0773 20130101; H02J 1/14 20130101;
G01R 31/086 20130101; H02J 13/00019 20200101; H04W 52/0206
20130101; H02J 13/00004 20200101; H04Q 11/0071 20130101; H02J
2310/12 20200101; Y02D 70/12 20180101; H02H 1/0007 20130101 |
International
Class: |
H02H 7/26 20060101
H02H007/26; H04B 10/077 20060101 H04B010/077; H04B 10/2575 20060101
H04B010/2575; H04B 10/80 20060101 H04B010/80; H02J 13/00 20060101
H02J013/00 |
Claims
1. A power consuming unit, comprising: a remote power input coupled
to a power conductor carrying current from a power distribution
circuit; and a remote switch circuit comprising a remote switch
input configured to receive a remote power connection signal; the
remote switch circuit configured to be closed to couple to the
remote power input; and the remote switch circuit further
configured to be opened to decouple from the remote power input;
and a switch control circuit coupled to the remote switch circuit
and configured to periodically open the remote switch circuit to
decouple from the remote power input; the power consuming unit
configured to: distribute one or more downlink communications
signals received from one or more downlink communications links, to
one or more client devices; and distribute one or more uplink
communications signals from the one or more client devices to one
or more uplink communications links.
2. The power consuming unit of claim 1, wherein the power consuming
unit further comprises a remote antenna unit within a distributed
communications system (DCS).
3. The power consuming unit of claim 1, further comprising an
antenna through which the power consuming unit distributes the one
or more downlink communications signals and through which the power
consuming unit receives the one or more uplink communications
signals.
4. The power consuming unit of claim 1, further comprising a remote
management communications input coupled to a management
communications link.
5. The power consuming unit of claim 4, wherein the switch control
circuit comprises a remote switch control input configured to
receive the remote power connection signal over the remote
management communications input, wherein the remote power
connection signal causes the switch control circuit to open the
remote switch circuit.
6. The power consuming unit of claim 1, wherein: the one or more
downlink communications links comprise one or more optical downlink
communications links; and the one or more uplink communications
links comprise one or more optical uplink communications links.
7. The power consuming unit of claim 6, further comprising: one or
more optical-to-electrical (O-E) converters configured to convert
the received one or more optical downlink communications signals
into one or more electrical downlink communications signals; and
one or more electrical-to-optical (E-O) converters configured to
convert received one or more electrical uplink communications
signals into the one or more optical uplink communications
signals.
8. The power consuming unit of claim 1, wherein the switch control
circuit is configured to detect a change in voltage level at the
remote power input from a first voltage level to a second voltage
level.
9. The power consuming unit of claim 8, wherein the switch control
circuit is configured to detect a change in the voltage level at
the remote power input from the second voltage level to the first
voltage level.
10. The power consuming unit of claim 1, further comprising: an
extended remote communications output configured to be coupled to
an extended downlink communications link coupled to an extended
remote unit; and an extended remote power output configured to be
coupled to an extended power conductor to carry current from the
power consuming unit to the extended remote unit.
11. A method of controlling a power consuming unit, the method
comprising: receiving current from a power distribution circuit at
a remote power input; responsive to a remote power connection
signal, periodically opening a remote switch circuit to decouple
power consuming elements of the power consuming unit from the
remote power input; periodically generating the remote power
connection signal with a switch control circuit; distributing one
or more downlink communications signals received from one or more
downlink communications links, to one or more client devices; and
distributing one or more uplink communications signals from the one
or more client devices to one or more uplink communications
links.
12. The method of claim 11, further comprising using an antenna
when distributing the one or more downlink communications
signals.
13. The method of claim 11, further comprising receiving through a
remote management communications input, the remote power connection
signal, wherein the remote power connection signal causes the
switch control circuit to open the remote switch circuit.
14. The method of claim 11, further comprising detecting a change
in voltage level at the remote power input from a first voltage
level to a second voltage level.
15. The method of claim 14, further comprising detecting a change
in the voltage level at the remote power input from the second
voltage level to the first voltage level.
16. The method of claim 11, further comprising coupling the power
consuming unit to an extended downlink communications link coupled
to an extended remote unit; and sending current from the power
consuming unit to the extended remote unit.
17. A power distribution system comprising: a power distribution
circuit comprising: a distribution power input configured to
receive current distributed by a power source; a distribution power
output configured to distribute the received current over a power
conductor coupled to an assigned remote unit among a plurality of
remote units; a distribution switch circuit coupled between the
distribution power input and the distribution power output, the
distribution switch circuit comprising a distribution switch
control input configured to receive a distribution power connection
control signal indicating a distribution power connection mode; the
distribution switch circuit configured to be closed to couple the
distribution power input to the distribution power output in
response to the distribution power connection mode indicating a
distribution power connect state; and the distribution switch
circuit further configured to be opened to decouple the
distribution power input from the distribution power output in
response to the distribution power connection mode indicating a
distribution power disconnect state; and a current measurement
circuit coupled to the distribution power output and comprising a
current measurement output; the current measurement circuit
configured to measure a current at the distribution power output
and generate a current measurement on the current measurement
output based on the measured current at the distribution power
output; and a controller circuit comprising: a current measurement
input communicatively coupled to a current measurement output of
the current measurement circuit of the power distribution circuit;
and the controller circuit configured to: generate the distribution
power connection control signal indicating the distribution power
connection mode to the distribution switch control input of the
power distribution circuit indicating the distribution power
connect state: determine if the measured current on a current
measurement input among the one or more current measurement inputs
of the power distribution circuit exceeds a predefined threshold
current level when the distribution switch circuit is closed to
couple the distribution power input to the distribution power
output; in response to the measured current of the power
distribution circuit exceeding the predefined threshold current
level, communicate the distribution power connection control signal
indicating the distribution power connection mode to the
distribution switch control input of the power distribution circuit
indicating the distribution power disconnect state; and communicate
a remote power connection signal comprising a change in voltage
levels indicating a remote power disconnect state to cause the
assigned remote unit to decouple current from the power conductor
of the power distribution circuit.
18. The power distribution system of claim 17, in response to the
measured current of the power distribution circuit not exceeding
the predefined threshold current level, communicate the
distribution power connection control signal comprising the
distribution power connection mode to the distribution switch
control input of the power distribution circuit indicating the
distribution power connect state.
19. The power distribution system of claim 17, wherein the
controller circuit is further configured to: communicate the remote
power connection signal comprising a remote power connection mode
indicating the remote power disconnect state before determining if
the measured current on the current measurement input exceeds the
predefined threshold current level.
20. The power distribution system of claim 17, wherein the
controller circuit is further configured to: communicate the remote
power connection signal comprising a remote power connection mode
indicating a remote power connect state over a distribution
management communications output coupled to the assigned remote
unit to the power distribution circuit to cause the assigned remote
unit to couple to the power conductor of the power distribution
circuit.
21. The power distribution system of claim 20, wherein the
controller circuit is configured to: communicate the remote power
connection signal comprising the remote power connection mode
indicating the remote power connect state after a predefined time
has elapsed after communicating the remote power connection signal
comprising the remote power connection mode indicating the remote
power disconnect state.
22. The power distribution system of claim 21, wherein the remote
power connection signal indicating the remote power connect state
comprises a change in voltage level that increases the voltage
level.
23. The power distribution system of claim 17, wherein the
predefined threshold current level is less than 200 milliAmps
(mA).
24. The power distribution system of claim 17, wherein the
predefined threshold current level is less than 100 milliAmps
(mA).
25. The power distribution system of claim 17, wherein the
controller circuit is further configured to periodically generate a
watchdog signal; and further comprising a watchdog controller
configured to: receive the watchdog signal; and in response to not
receiving the watchdog signal within a predefined time period,
cause the distribution power connection control signal to indicate
the distribution power disconnect state.
26. A power distribution system comprising: a power distribution
circuit comprising: a distribution power input configured to
receive current distributed by a power source; a distribution power
output configured to distribute the received current over a power
conductor coupled to an assigned remote unit among a plurality of
remote units; a distribution switch circuit coupled between the
distribution power input and the distribution power output, the
distribution switch circuit comprising a distribution switch
control input configured to receive a distribution power connection
control signal indicating a distribution power connection mode; the
distribution switch circuit configured to be closed to couple the
distribution power input to the distribution power output in
response to the distribution power connection mode indicating a
distribution power connect state; and the distribution switch
circuit further configured to be opened to decouple the
distribution power input from the distribution power output in
response to the distribution power connection mode indicating a
distribution power disconnect state; and a current measurement
circuit coupled to the distribution power output and comprising a
current measurement output; the current measurement circuit
configured to measure a current at the distribution power output
and generate a current measurement on the current measurement
output based on the measured current at the distribution power
output; and a controller circuit comprising: a current measurement
input communicatively coupled to a current measurement output of
the power distribution circuit; and the controller circuit
configured to: generate the distribution power connection control
signal indicating the distribution power connection mode to the
distribution switch control input of the power distribution circuit
indicating the distribution power connect state; determine if the
measured current on a current measurement input among the one or
more current measurement inputs of the power distribution circuit
exceeds a predefined threshold current level when the distribution
switch circuit is closed to couple the distribution power input to
the distribution power output; in response to the measured current
of the power distribution circuit exceeding the predefined
threshold current level, communicate the distribution power
connection control signal indicating the distribution power
connection mode to the distribution switch control input of the
power distribution circuit indicating the distribution power
disconnect state; lower a voltage level on the distribution power
output from a first voltage level to a second voltage level
distributing the received current over the power conductor coupled
to the assigned remote unit; and raise the voltage level on the
distribution power output from the second voltage level to the
first voltage level distributing the received current over the
power conductor coupled to the assigned remote unit.
Description
PRIORITY
[0001] This application is a continuation of International
Application PCT/IL2018/050368, filed Mar. 29, 2018, which claims
priority to U.S. Provisional Patent Application No. 62/479,656 and
entitled "Safety Power Disconnection For Power Distribution Over
Power Conductors To Power Consuming Devices," filed on Mar. 31,
2017, which are incorporated herein by reference in their
entireties.
BACKGROUND
[0002] The disclosure relates generally to distribution of power to
one or more power consuming devices over power wiring, and more
particularly to remote distribution of power to remote units in a
power distribution system, which may include distributed
communications systems (DCS) such as distributed antenna systems
(DAS) for example, for operation of power consuming components of
the remote units.
[0003] Wireless customers are increasingly demanding wireless
communications services, such as cellular communications services
and Wi-Fi services. Thus, small cells, and more recently Wi-Fi
services, are being deployed indoors. At the same time, some
wireless customers use their wireless communication devices in
areas that are poorly serviced by conventional cellular networks,
such as inside certain buildings or areas where there is little
cellular coverage. One response to the intersection of these two
concerns has been the use of distributed antenna systems (DASs).
DASs include remote antenna units (RAUs) configured to receive and
transmit communications signals to client devices within the
antenna range of the RAUs. DASs can be particularly useful when
deployed inside buildings or other indoor environments where the
wireless communication devices may not otherwise be able to
effectively receive radio frequency (RF) signals from a source.
[0004] In this regard, FIG. 1 illustrates a wireless distributed
communications system (WDCS) 100 that is configured to distribute
communications services to remote coverage areas 102(1)-102(N),
where "N" is the number of remote coverage areas. The WDCS 100 in
FIG. 1 is provided in the form of a DAS 104. The DAS 104 can be
configured to support a variety of communications services that can
include cellular communications services, wireless communications
services, such as RF identification (RFID) tracking, Wireless
Fidelity (Wi-Fi), local area network (LAN), and wireless LAN
(WLAN), wireless solutions (Bluetooth, Wi-Fi Global Positioning
System (GPS) signal-based, and others) for location-based services,
and combinations thereof, as examples. The remote coverage areas
102(1)-102(N) are created by and centered on RAUs 106(1)-106(N)
connected to a central unit 108 (e.g., a head-end controller, a
central unit, or a head-end unit). The central unit 108 may be
communicatively coupled to a source transceiver 110, such as for
example, a base transceiver station (BTS) or a baseband unit (BBU).
In this regard, the central unit 108 receives downlink
communications signals 112D from the source transceiver 110 to be
distributed to the RAUs 106(1)-106(N). The downlink communications
signals 112D can include data communications signals and/or
communication signaling signals, as examples. The central unit 108
is configured with filtering circuits and/or other signal
processing circuits that are configured to support a specific
number of communications services in a particular frequency
bandwidth (i.e., frequency communications bands). The downlink
communications signals 112D are communicated by the central unit
108 over a communications link 114 over their frequency to the RAUs
106(1)-106(N).
[0005] With continuing reference to FIG. 1, the RAUs 106(1)-106(N)
are configured to receive the downlink communications signals 112D
from the central unit 108 over the communications link 114. The
downlink communications signals 112D are configured to be
distributed to the respective remote coverage areas 102(1)-102(N)
of the RAUs 106(1)-106(N). The RAUs 106(1)-106(N) are also
configured with filters and other signal processing circuits that
are configured to support all or a subset of the specific
communications services (i.e., frequency communications bands)
supported by the central unit 108. In a non-limiting example, the
communications link 114 may be a wired communications link, a
wireless communications link, or an optical fiber-based
communications link. Each of the RAUs 106(1)-106(N) may include an
RF transmitter/receiver 116(1)-116(N) and a respective antenna
118(1)-118(N) operably connected to the RF transmitter/receiver
116(1)-116(N) to wirelessly distribute the communications services
to user equipment (UE) 120 within the respective remote coverage
areas 102(1)-102(N). The RAUs 106(1)-106(N) are also configured to
receive uplink communications signals 112U from the UE 120 in the
respective remote coverage areas 102(1)-102(N) to be distributed to
the source transceiver 110.
[0006] Because the RAUs 106(1)-106(N) include components that
require power to operate, such as the RF transmitter/receivers
116(1)-116(N) for example, it is necessary to provide power to the
RAUs 106(1)-106(N). In one example, each RAU 106(1)-106(N) may
receive power from a local power source. In another example, the
RAUs 106(1)-106(N) may be powered remotely from a remote power
source(s). For example, the central unit 108 may include a power
source 122 that is configured to remotely supply power over the
communications links 114 to the RAUs 106(1)-106(N). For example,
the communications links 114 may be cable that includes electrical
conductors for carrying current (e.g., direct current (DC)) to the
RAUs 106(1)-106(N). If the WDCS 100 is an optical fiber-based WDCS
in which the communications links 114 include optical fibers, the
communications links 114 may by a "hybrid" cable that includes
optical fibers for carrying the downlink and uplink communications
signals 112D, 112U and separate electrical conductors for carrying
current to the RAUs 106(1)-106(N).
[0007] Some regulations, such as IEC 60950-21, may limit the amount
of direct current (DC) that is remote delivered by the power source
122 over the communications links 114 to less than the amount
needed to power the RAUs 106(1)-106(N) during peak power
consumption periods for safety reasons, such as in the event a
human contacts the wire. One solution to remote power distribution
limitations is to employ multiple conductors and split current from
the power source 122 over the multiple conductors, such that the
current on any one electrical conductor is below the regulated
limit. Another solution includes delivering remote power at a
higher voltage so that a lower current can be distributed at the
same power level. For example, assume that 300 Watts of power is to
be supplied to a RAU 106(1)-106(N) by the power source 122 through
a communications link 114. If the voltage of the power source 122
is 60 Volts (V), the current will be 5 Amperes (A) (i.e., 300 W/60
V). However, if a 400 Volt power source 122 is used, then the
current flowing through the wires will be 0.75 A. However,
delivering high voltage through electrical conductors may be
further regulated to prevent an undesired current from flowing
through a human in the event that a human contacts the electrical
conductor. Thus, these safety measures may require other
protections, such as the use of protection conduits, which may make
installations more difficult and add cost.
[0008] No admission is made that any reference cited herein
constitutes prior art. Applicant expressly reserves the right to
challenge the accuracy and pertinency of any cited documents.
SUMMARY
[0009] Embodiments of the disclosure relate to safety power
disconnection for power distribution over power conductors to power
consuming devices systems. As a non-limiting example, a power
distribution may be provided in a distributed communications
systems (DCS). For example, the DCS may be a wireless DCS, such as
a distributed antenna system (DAS) that is configured to distribute
communications signals, including wireless communications signals,
from a central unit to a plurality of remote units over physical
communications media, to then be distributed from the remote units
wirelessly to client devices in wireless communication range of a
remote unit. In exemplary aspects disclosed herein, the DCS
includes one or more power distribution systems each configured to
remotely distribute power from a power source over current carrying
electrical conductors ("power conductors") to remote units to
provide power-to-power consuming components of the remote units for
operation. For example, a power distribution system may be
installed on each floor of a multi-floor building in which the DCS
is installed to provide power to the remote units installed on a
given floor. Each power distribution system includes a current
measurement circuit configured to measure current delivered by the
power source over the power conductors to remote units. Each power
distribution system also includes a controller circuit configured
to communicate over a management communications link to the remote
units receiving power from the power distribution circuit. The
remote unit is configured to be decoupled from the power conductors
from its power consuming components thereby disconnecting the load
of the remote unit from the power distribution system. The current
measurement circuit then measures current flowing on the power
conductors and provides a current measurement to the controller
circuit. The controller circuit is configured to disconnect the
power source from the power conductors for safety reasons in
response to detection of a load based on detecting a current from
the power source in excess of a threshold current level. For
example, a person contacting the power conductors will present a
load to the power source that will cause a current to flow from the
power source over the power conductors. If another load is not
contacting the power conductors, no current (or only a small amount
current due to current leakages for example) should flow from the
power source over the power conductors. The controller circuit can
be configured to wait a period of time and/or until a manual reset
instruction is received, before connecting the power source from
the power conductors and remote unit coupling its power consuming
components to the power conductors to once again allow current to
flow from the power source to the remote units serviced by the
power distribution system.
[0010] In this regard, in one exemplary aspect, a power
distribution system is disclosed. The power distribution system
comprises one or more power distribution circuits. The one or more
power distribution circuits each comprise a distribution power
input configured to receive current distributed by a power source.
The one or more power distribution circuits each also comprise a
distribution power output configured to distribute the received
current over a power conductor coupled to an assigned remote unit
among a plurality of remote units. The one or more power
distribution circuits each also comprise a distribution switch
circuit coupled between the distribution power input and the
distribution power output. The distribution switch circuit
comprises a distribution switch control input configured to receive
a distribution power connection control signal indicating a
distribution power connection mode. The distribution switch circuit
is configured to be closed to couple the distribution power input
to the distribution power output in response to the distribution
power connection mode indicating a distribution power connect
state. The distribution switch circuit is further configured to be
opened to decouple the distribution power input from the
distribution power output in response to the distribution power
connection mode indicating a distribution power disconnect state.
The one or more power distribution circuits each also comprise a
current measurement circuit coupled to the distribution power
output and comprising a current measurement output. The current
measurement circuit is configured to measure a current at the
distribution power output and generate a current measurement on the
current measurement output based on the measured current at the
distribution power output. The power distribution system also
comprises a controller circuit. The controller circuit comprises
one or more current measurement inputs communicatively coupled to
the one or more current measurement outputs of the one or more
current measurement circuits of the one or more power distribution
circuits. The controller circuit is configured to, for a power
distribution circuit among the one or more power distribution
circuits, generate the distribution power connection control signal
indicating the distribution power connection mode to the
distribution switch control input of the power distribution circuit
indicating the distribution power connect state, determine if the
measured current on a current measurement input among the one or
more current measurement inputs of the power distribution circuit
exceeds a predefined threshold current level when the distribution
switch circuit is closed to couple the distribution power input to
the distribution power output; and in response to the measured
current of the power distribution circuit exceeding the predefined
threshold current level, communicate the distribution power
connection control signal indicating the distribution power
connection mode to the distribution switch control input of the
power distribution circuit indicating the distribution power
disconnect state.
[0011] An additional aspect of the disclosure relates to a method
of disconnecting current from a power source. The method comprises
decoupling current from a power conductor to a remote unit. The
method further comprises measuring a current received from a power
source coupled to the power conductor. The method further comprises
determining if the measured current exceeds a predefined threshold
current level. The method further comprises, in response to the
measured current exceeding the predefined threshold current level,
communicating a distribution power connection control signal
comprising a distribution power connection mode indicating a
distribution power disconnect state to cause the power conductor to
be decoupled from the power source.
[0012] An additional aspect of the disclosure relates to a
distributed communications system (DCS). The DCS comprises a
central unit. The central unit is configured to distribute received
one or more downlink communications signals over one or more
downlink communications links to one or more remote units. The
central unit is also configured to distribute received one or more
uplink communications signals from the one or more remote units
from one or more uplink communications links to one or more source
communications outputs. The DCS also comprises a plurality of
remote units. Each remote unit among the plurality of remote units
comprises a remote power input coupled to a power conductor
carrying current from a power distribution circuit. Each remote
unit among the plurality of remote units also comprises a remote
switch control circuit configured to generate a remote power
connection signal indicating a remote power connection mode. Each
remote unit among the plurality of remote units also comprises a
remote switch circuit comprising a remote switch input configured
to receive the remote power connection signal. The remote switch
circuit is configured to be closed to couple to the remote power
input in response to the remote power connection mode indicating a
remote power connect state. The remote switch circuit is further
configured to be opened to decouple from the remote power input in
response to the remote power connection mode indicating a remote
power disconnect state. The remote unit is configured to distribute
the received one or more downlink communications signals received
from the one or more downlink communications links, to one or more
client devices. The remote unit is also configured to distribute
the received one or more uplink communications signals from the one
or more client devices to the one or more uplink communications
links. The DCS also comprises a power distribution system. The
power distribution system comprises one or more power distribution
circuits. Each power distribution circuit of the one or more power
distribution circuits comprises a distribution power input
configured to receive current distributed by a power source. Each
power distribution circuit of the one or more power distribution
circuits also comprises a distribution power output configured to
distribute the received current over a power conductor coupled to
an assigned remote unit among a plurality of remote units. Each
power distribution circuit of the one or more power distribution
circuits also comprises a distribution switch circuit coupled
between the distribution power input and the distribution power
output, the distribution switch circuit comprising a distribution
switch control input configured to receive a distribution power
connection control signal indicating a distribution power
connection mode. The distribution switch circuit is configured to
be closed to couple the distribution power input to the
distribution power output in response to the distribution power
connection mode indicating a distribution power connect state. The
distribution switch circuit is further configured to be opened to
decouple the distribution power input from the distribution power
output in response to the distribution power connection mode
indicating a distribution power disconnect state. Each power
distribution circuit of the one or more power distribution circuits
also comprises a current measurement circuit coupled to the
distribution power output and comprising a current measurement
output. The current measurement circuit configured to measure a
current at the distribution power output and generate a current
measurement on the current measurement output based on the measured
current at the distribution power output. The power distribution
system also comprises a controller circuit. The controller circuit
comprises one or more current measurement inputs communicatively
coupled to the one or more current measurement outputs of the one
or more current measurement circuits of the one or more power
distribution circuits. The controller circuit is configured to, for
a power distribution circuit among the one or more power
distribution circuits: generate the distribution power connection
control signal indicating the distribution power connection mode to
the distribution switch control input of the power distribution
circuit indicating the distribution power connect state; determine
if the measured current on a current measurement input among the
one or more current measurement inputs of the power distribution
circuit exceeds a predefined threshold current level; and in
response to the measured current of the power distribution circuit
exceeding the predefined threshold current level, communicate the
distribution power connection control signal comprising the
distribution power connection mode to the distribution switch
control input of the power distribution circuit indicating the
distribution power disconnect state.
[0013] Additional features and advantages will be set forth in the
detailed description which follows and, in part, will be readily
apparent to those skilled in the art from the description or
recognized by practicing the embodiments as described in the
written description and claims hereof, as well as the appended
drawings.
[0014] It is to be understood that both the foregoing general
description and the following detailed description are merely
exemplary and are intended to provide an overview or framework to
understand the nature and character of the claims.
[0015] The accompanying drawings are included to provide a further
understanding of the disclosure, and are incorporated in and
constitute a part of this specification. The drawings illustrate
one or more embodiment(s), and together with the description serve
to explain principles and operation of the various embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic diagram of an exemplary wireless
distributed communications system (DCS) in the form of a
distributed antenna system (DAS);
[0017] FIG. 2 is a schematic diagram of an exemplary optical-fiber
based DCS in the form of a DAS configured to distribute
communications signals between a central unit and a plurality of
remote units, and that can include one or more power distribution
systems configured to distribute power to a plurality of remote
units and provide a safety power disconnect of the power source to
remote units;
[0018] FIG. 3A is a partially schematic cut-away diagram of an
exemplary building infrastructure in which a DCS in FIG. 2 can be
provided;
[0019] FIG. 3B is a more detailed schematic diagram of the DCS in
FIG. 3A:
[0020] FIG. 4 is a schematic diagram illustrating a power
distribution system that can be included in the DCS in FIGS. 2-3B
as an example, wherein the power distribution system is configured
to provide safety power disconnect of the power source to a remote
unit in response to a measured current from the connected power
source when the remote unit is decoupled from the power source
during a testing phase;
[0021] FIG. 5 is a timing diagram illustrating an exemplary timing
sequence of the controller circuit in the power distribution system
in the DCS in FIG. 4;
[0022] FIG. 6 is a flowchart illustrating an exemplary process of
the controller circuit in the power distribution system of the DCS
in FIG. 4 coupling the remote unit during a normal operation phase
and instructing the remote unit to decouple from the power source
during testing phases to then measure current from the power source
during a testing phase;
[0023] FIG. 7 is a graph illustrating exemplary safe and unsafe
regions of body current for a given current impulse time,
[0024] FIG. 8 is a schematic diagram illustrating the DCS in FIG. 4
with the power distribution circuit configured to distribute power
from a power source to a plurality of remote units to provide power
for operation of the remote units, and provide a safety power
disconnect of the power source to remote units in response to a
measured current from the power source;
[0025] FIG. 9 is a schematic diagram illustrating an exemplary
power distribution system that can be employed as the power
distribution systems in the DCS in FIG. 8:
[0026] FIG. 10 is a schematic diagram illustrating additional
exemplary detail of the controller circuit of the power
distribution system in FIG. 8:
[0027] FIG. 11 is a diagram of another exemplary power distribution
system that can be provided in the DCS in FIGS. 2 and 3, wherein
the power distribution system is configured to provide safety power
disconnect of the power source to a remote unit in response to a
measured differential current from the connected power source when
the remote unit is decoupled from the power source during a testing
phase; and
[0028] FIG. 12 is a schematic diagram of a generalized
representation of an exemplary controller that can be included in
any component in a DCS, including but not limited to the controller
circuits in the power distribution systems for coupling a remote
unit to a power source during a normal operation phase and
instructing the remote unit to decouple from the power source
during testing phases to then measure current from the power source
during a testing phase, wherein an exemplary computer system is
adapted to execute instructions from an exemplary computer readable
link.
DETAILED DESCRIPTION
[0029] Embodiments of the disclosure relate to safety power
disconnection for power distribution over power conductors to power
consuming devices systems. As a non-limiting example, a power
distribution may be provided in a distributed communications
systems (DCS). For example, the DCS may be a wireless DCS, such as
a distributed antenna system (DAS) that is configured to distribute
communications signals, including wireless communications signals,
from a central unit to a plurality of remote units over physical
communications media, to then be distributed from the remote units
wirelessly to client devices in wireless communication range of a
remote unit. In exemplary aspects disclosed herein, the DCS
includes one or more power distribution systems each configured to
remotely distribute power from a power source over current carrying
electrical conductors ("power conductors") to remote units to
provide power-to-power consuming components of the remote units for
operation. For example, a power distribution system may be
installed on each floor of a multi-floor building in which the DCS
is installed to provide power to the remote units installed on a
given floor. Each power distribution system includes a current
measurement circuit configured to measure current delivered by the
power source over the power conductors to remote units. Each power
distribution system also includes a controller circuit configured
to communicate over a management communications link to the remote
units receiving power from the power distribution circuit. The
remote unit is configured to be decoupled from the power conductors
from its power consuming components thereby disconnecting the load
of the remote unit from the power distribution system. The current
measurement circuit then measures current flowing on the power
conductors and provides a current measurement to the controller
circuit. The controller circuit is configured to disconnect the
power source from the power conductors for safety reasons in
response to detection of a load based on detecting a current from
the power source in excess of a threshold current level. For
example, a person contacting the power conductors will present a
load to the power source that will cause a current to flow from the
power source over the power conductors. If another load is not
contacting the power conductors, no current (or only a small amount
current due to current leakages for example) should flow from the
power source over the power conductors. The controller circuit can
be configured to wait a period of time and/or until a manual reset
instruction is received, before connecting the power source from
the power conductors and remote unit coupling its power consuming
components to the power conductors to once again allow current to
flow from the power source to the remote units serviced by the
power distribution system.
[0030] Before discussing exemplary details of power distribution
systems, including power distribution systems that can be included
in a DCS for remotely distributing power to remote units and
provide safety power disconnect of a power source to the remote
units starting at FIG. 4, an exemplary power distribution system
that can include remote power distribution is described in FIGS.
2-3B.
[0031] In this regard, FIG. 2 is a schematic diagram of such an
exemplary power distribution system 250. In this example, the power
distribution system 250 is provided in the form of a DCS 200, which
is a distributed antenna system (DAS) 202 in this example. Note
that the power distribution circuit 250 is not limited to a DCS or
being provided in a DCS. A DAS is a system that is configured to
distribute communications signals, including wireless
communications signals, from a central unit to a plurality of
remote units over physical communications media, to then be
distributed from the remote units wirelessly to client devices in
wireless communication range of a remote unit. The DAS 202 in this
example is an optical fiber-based DAS that is comprised of three
(3) main components. One or more radio interface circuits provided
in the form of radio interface modules (RIMs) 204(1)-204(T) are
provided in a central unit 206 to receive and process downlink
electrical communications signals 208D(1)-208D(S) prior to optical
conversion into downlink optical communications signals. The
downlink electrical communications signals 208D(1)-208D(S) may be
received from a base transceiver station (BTS) or baseband unit
(BBU) as examples. The downlink electrical communications signals
208D(1)-208D(S) may be analog signals or digital signals that can
be sampled and processed as digital information. The RIMs
204(1)-204(T) provide both downlink and uplink interfaces for
signal processing. The notations "1-S" and "1-T" indicate that any
number of the referenced component, 1-S and 1-T, respectively, may
be provided.
[0032] With continuing reference to FIG. 2, the central unit 206 is
configured to accept the plurality of RIMs 204(1)-204(T) as modular
components that can easily be installed and removed or replaced in
a chassis. In one embodiment, the central unit 206 is configured to
support up to twelve (12) RIMs 204(1)-204(12). Each RIM
204(1)-204(T) can be designed to support a particular type of radio
source or range of radio sources (i.e., frequencies) to provide
flexibility in configuring the central unit 206 and the DAS 202 to
support the desired radio sources. For example, one RIM 204 may be
configured to support the Personal Communication Services (PCS)
radio band. Another RIM 204 may be configured to support the 700
MHz radio band. In this example, by inclusion of these RIMs 204,
the central unit 206 could be configured to support and distribute
communications signals, including those for the communications
services and communications bands described above as examples.
[0033] The RIMs 204(1)-204(T) may be provided in the central unit
206 that support any frequencies desired, including but not limited
to licensed US FCC and Industry Canada frequencies (824-849 MHz on
uplink and 869-894 MHz on downlink), US FCC and Industry Canada
frequencies (1850-1915 MHz on uplink and 1930-1995 MHz on
downlink), US FCC and Industry Canada frequencies (1710-1755 MHz on
uplink and 2110-2155 MHz on downlink), US FCC frequencies (698-716
MHz and 776-787 MHz on uplink and 728-746 MHz on downlink), EU R
& TTE frequencies (880-915 MHz on uplink and 925-960 MHz on
downlink), EU R & TTE frequencies (1710-1785 MHz on uplink and
1805-1880 MHz on downlink), EU R & TTE frequencies (1920-1980
MHz on uplink and 2110-2170 MHz on downlink), US FCC frequencies
(806-824 MHz on uplink and 851-869 MHz on downlink), US FCC
frequencies (896-901 MHz on uplink and 929-941 MHz on downlink), US
FCC frequencies (793-805 MHz on uplink and 763-775 MHz on
downlink), and US FCC frequencies (2495-2690 MHz on uplink and
downlink).
[0034] With continuing reference to FIG. 2, the received downlink
electrical communications signals 208D(1)-208D(S) are provided to a
plurality of optical interfaces provided in the form of optical
interface modules (OIMs) 210(1)-210(W) in this embodiment to
convert the downlink electrical communications signals
208D(1)-208D(S) ("downlink electrical communications signals
208D(1)-208D(S)") into downlink optical communications signals
212D(1)-212D(S). The notation "1-W" indicates that any number of
the referenced component 1-W may be provided. The OIMs 210 may
include one or more optical interface components (OICs) that
contain electrical-to-optical (E-O) converters 216(1)-216(W) to
convert the received downlink electrical communications signals
208D(1)-208D(S) into the downlink optical communications signals
212D(1)-212D(S). The OIMs 210 support the radio bands that can be
provided by the RIMs 204, including the examples previously
described above. The downlink optical communications signals
212D(1)-212D(S) are communicated over a downlink optical fiber
communications link 214D to a plurality of remote units
218(1)-218(X) provided in the form of remote antenna units in this
example. The notation "1-X" indicates that any number of the
referenced component 1-X may be provided. One or more of the
downlink optical communications signals 212D(1)-212D(S) can be
distributed to each remote unit 218(1)-218(X). Thus, the
distribution of the downlink optical communications signals
212D(1)-212D(S) from the central unit 206 to the remote units
218(1)-218(X) is in a point-to-multipoint configuration in this
example.
[0035] With continuing reference to FIG. 2, the remote units
218(1)-218(X) include optical-to-electrical (O-E) converters
220(1)-220(X) configured to convert the one or more received
downlink optical communications signals 212D(1)-212D(S) back into
the downlink electrical communications signals 208D(1)-208D(S) to
be wirelessly radiated through antennas 222(1)-222(X) in the remote
units 218(1)-218(X) to user equipment (not shown) in the reception
range of the antennas 222(1)-222(X). The OIMs 210 may also include
O-E converters 224(1)-224(W) to convert the received uplink optical
communications signals 212U(1)-212U(X) from the remote units
218(1)-218(X) into the uplink electrical communications signals
226U(1)-226U(S) as will be described in more detail below.
[0036] With continuing reference to FIG. 2, the remote units
218(1)-218(X) are also configured to receive uplink electrical
communications signals 228U(I)-228U(X) received by the respective
antennas 222(1)-222(X) from client devices in wireless
communication range of the remote units 218(1)-218(X). The uplink
electrical communications signals 228U(1)-228U(S) may be analog
signals or digital signals that can be sampled and processed as
digital information. The remote units 218(1)-218(X) include E-O
converters 229(1)-229(X) to convert the received uplink electrical
communications signals 228U(1)-228U(X) into uplink optical
communications signals 212U(1)-212U(X). The remote units
218(1)-218(X) distribute the uplink optical communications signals
212U(1)-212U(X) over an uplink optical fiber communication link
214U to the OIMs 210(1)-210(W) in the central unit 206. The O-E
converters 224(1)-224(W) convert the received uplink optical
communications signals 212U(1)-212U(X) into uplink electrical
communications signals 230U(1)-230U(X), which are processed by the
RIMs 204(1)-204(T) and provided as the uplink electrical
communications signals 230U(1)-230U(X) to a source transceiver such
as a base transceiver station (BTS) or baseband unit (BBU).
[0037] Note that the downlink optical fiber communications link
214D and the uplink optical fiber communications link 214U coupled
between the central unit 206 and the remote units 218(1)-218(X) may
be a common optical fiber communications link, wherein for example,
wave division multiplexing (WDM) may be employed to carry the
downlink optical communications signals 212D(1)-212D(S) and the
uplink optical communications signals 212U(1)-212U(X) on the same
optical fiber communications link. Alternatively, the downlink
optical fiber communications link 214D and the uplink optical fiber
communications link 214U coupled between the central unit 206 and
the remote units 218(1)-218(X) may be single, separate optical
fiber communications link, wherein for example, wave division
multiplexing (WDM) may be employed to carry the downlink optical
communications signals 212D(1)-212D(S) on one common downlink
optical fiber and the uplink optical communications signals
212U(1)-212U(X) carried on a separate, only uplink optical fiber.
Alternatively, the downlink optical fiber communications link 214D
and the uplink optical fiber communications link 214U coupled
between the central unit 206 and the remote units 218(1)-218(X) may
be separate optical fibers dedicated to and providing a separate
communications link between the central unit 206 and each remote
unit 218(1)-218(X).
[0038] The DCS 200 in FIG. 2 can be provided in an indoor
environment as illustrated in FIG. 3A. FIG. 3A is a partially
schematic cut-away diagram of a building infrastructure 232
employing the DCS 200. FIG. 3B is a schematic diagram of the DCS
200 installed according to the building infrastructure 232 in FIG.
3A.
[0039] With reference to FIG. 3A, the building infrastructure 232
in this embodiment includes a first (ground) floor 234(1), a second
floor 234(2), and a Fth floor 234(F), where `F` can represent any
number of floors. The floors 234(1)-234(F) are serviced by the
central unit 206 to provide antenna coverage areas 236 in the
building infrastructure 232. The central unit 206 is
communicatively coupled to a signal source 238, such as a BTS or
BBU, to receive the downlink electrical communications signals
208D(1)-208D(S). The central unit 206 is communicatively coupled to
the remote units 218(1)-218(X) to receive optical uplink
communications signals 212U(1)-212U(X) from the remote units
218(1)-218(X) as previously described in FIG. 2A. The downlink and
uplink optical communications signals 212D(1)-212D(S),
212U(1)-212U(X) are distributed between the central unit 206 and
the remote units 218(1)-218(X) over a riser cable 240 in this
example. The riser cable 240 may be routed through interconnect
units (ICUs) 242(1)-242(F) dedicated to each floor 234(1)-234(F)
for routing the downlink and uplink optical communications signals
212D(1)-212D(S), 212U(1)-212U(X) to the remote units 218(1)-218(X).
The ICUs 242(1)-242(F) may also include respective power
distribution circuits 244(1)-244(F) that include power sources as
part of the power distribution system 250, wherein the power
distribution circuits 244(1)-244(F) are configured to distribute
power remotely to the remote units 218(1)-218(X) to provide power
for operating the power consuming components in the remote units
218(1)-218(X). For example, array cables 245(1)-245(F) may be
provided and coupled between the ICUs 242(1)-242(F) that contain
both optical fibers to provide the respective downlink and uplink
optical fiber communications media 214D(1)-214D(F), 214U(1)-214U(F)
and power conductors 246(1)-246(F) (e.g., electrical wire) to carry
current from the respective power distribution circuits
244(1)-244(F) to the remote units 218(1)-218(X).
[0040] With reference to the DCS 200 shown in FIG. 3B, the central
unit 206 may include a power supply circuit 252 to provide power to
the RIMs 204(1)-204(T), the OIMs 210(1)-210(W), and radio
distribution circuits (RDCs) 254, 256. The downlink electrical
communications signals 208D(1)-208D(S) and the uplink electrical
communications signals 226U(1)-226U(S) are routed from between the
RIMs 204(1)-204(T) and the OIMs 210(1)-210(W) through RDCs 254,
256. In one embodiment, the RDCs 254, 256 can support sectorization
in the DCS 200, meaning that only certain downlink electrical
communications signals 208D(1)-208D(S) are routed to certain RIMs
204(1)-204(T). A power supply circuit 258 may also be provided to
provide power to the OIMs 210(1)-210(W). An interface 260, which
may include web and network management system (NMS) interfaces, may
also be provided to allow configuration and communication to the
components of the central unit 206. A microcontroller,
microprocessor, or other control circuitry, called a head-end
controller (HEC) 262 may be included in central unit 206 to provide
control operations for the central unit 206 and the DCS 200.
[0041] As discussed above in reference to FIG. 3A and with
continuing reference to FIG. 3B, the power distribution circuits
244(1)-244(F) may be provided in the DCS 200 to remotely supply
power to the remote units 218(1)-218(X) for operation. For example,
the power distribution circuits 244(1)-244(F) may be configured to
supply direct current (DC) power due to relative short distances
and as a safer option than distributing alternating current (AC)
power. Further, distributing DC power may avoid the need to provide
AC-DC conversion circuitry in the remote units 218(1)-218(X) saving
area and cost. Remotely distributing power to the remote units
218(1)-218(X) may be desired if it is difficult or not possible to
locally provide power to the remote units 218(1)-218(X) in their
installed locations. For example, the remote units 218(1)-218(X)
may be installed in ceilings or on walls of a building. Even if
local power is available, the local power may not be capable of
supplying enough power-to-power the number of remote units
218(1)-218(X) desired. However, regulations may also limit the
amount of DC that is remotely delivered by the power distribution
circuits 244(1)-244(F) over the power conductors 246(1)-246(F) to
less than the amount needed to power the remote units 218(1)-218(X)
during peak power consumption periods for safety reasons, such as
in the event a human contacts the power conductors 246(1)-246(F).
One solution to these remote power distribution limitations is to
employ multiple power conductors 246(1)-246(F) and split current
from the power distribution circuits 244(1)-244(F) over the
multiple power conductors 246(1)-246(F) as shown, such that the
current on any one power conductor 246(1)-246(F) is below the
regulated limit. Another solution includes delivering remote power
at a higher voltage so that a lower current can be distributed at
the same power level. For example, assume that 300 Watts of power
is to be supplied to a remote unit 218(1)-218(X) by a power
distribution circuit 244(1)-244(F) through a respective power
conductor 246(1)-246(F). If the voltage of the power distribution
circuit 244(1)-244(F) is 60 Volts (V), the current will be 5
Amperes (A) (i.e., 300 W/60 V). However, if a 400 Volt is employed,
then the current flowing through the wires will be 0.75 A. However,
delivering high voltage through power conductors 246(1)-246(F) may
be further regulated to prevent an undesired current from flowing
through a human in the event that a human contacts the power
conductor 246(1)-246(F). Thus, these safety measures may require
other protections, such as the use of protection conduits for the
array cables 245(1)-245(F), which may make installations of the DSC
200 more difficult and add cost.
[0042] In this regard, FIG. 4 is a schematic diagram illustrating a
power distribution circuit 244 of the power distribution system 250
in the form of the DCS 200 in FIGS. 2-3B. The power distribution
circuit 244 in FIG. 4 can be any of the power distribution circuits
244(1)-244(F) in FIGS. 3A and 3B. The power distribution circuit
244 includes a power source 400 that is configured to supply power
(i.e., current I.sub.1) to be distributed over the power conductors
246+, 246- to a load 401 of the remote unit 218 to provide power to
the remote unit 218 for operation of its consuming components. For
example, the power source 400 may be a DC/DC power supply (e.g.,
48V DC/350V DC) or AC/DC power supply (e.g., AC/350 V DC). The
power source 400 may be included in the same housing or chassis as
the power distribution circuit 244, or separate from the power
distribution circuit 244. As will be discussed in more detail
below, the power distribution circuit 244 illustrated in FIG. 4 is
configured to provide safety power disconnect of the power source
400 from the power conductors 246+, 246- in response to a measured
current I.sub.2 from the connected power source 400 when the remote
unit 218 is decoupled from the power source 400 during a testing
phase. The power distribution circuit 244 includes a current
measurement circuit 402 configured to measure the current I.sub.2
delivered by the power source 400 to a distribution power output
403 coupled to the power conductors 246+, 246- as an indication of
a safety condition as to whether an external load, such as a human,
is in contact on the power conductors 246+, 246-. If another load
is not contacting the power conductors 246+, 246-, this means no
current or only a small amount of current, due to current leakages
for example, should flow from the power source 400 to the power
conductors 246+, 246-. However, if an external load 418, such as a
person, is contacting the power conductors 246+, 246-, this load
418 will present a load to the power source 400 that will cause the
current I.sub.2 to flow from the power source 400 over the power
conductors 246+, 246-. This current I.sub.2 can be detected as a
method of detecting an external load 418, such as a human, in
contact with the power conductors 246+, 246- to cause the power
distribution circuit 244 to decouple the power source 400 from the
power conductors 246+, 246- as a safety measure.
[0043] In this regard, with reference to FIG. 4, the power
distribution circuit 244 includes a controller circuit 404. The
controller circuit 404 is configured to send a distribution power
connection control signal 406 indicating a distribution power
connection state to close a distribution switch circuit 408 to
couple the power source 400 to the current measurement circuit 402.
The closing of the distribution switch circuit 408 allows current
I.sub.1 to be drawn from the power source 400 and be carried by the
power conductor 246+ to a remote power input 409 of the remote unit
218. To determine if an external load 418 other than the remote
circuit 218, such as a human, is contacting the power conductors
246+, 246-, the controller circuit 404 could be configured to
communicate over a management communications link 410 to the remote
unit 218. The management communications link 410 may be electrical
conductors (e.g. copper wire) or optical fiber medium as examples.
The management communications link 410 may be a bidirectional
communications link configured to carry a full duplex signal at a
carrier frequency, such as 1.5 MHz for example. The controller
circuit 404 is configured to send a remote power connection signal
412 indicating a remote power disconnect state to a switch control
circuit 414 coupled to the management communications link 410. In
response, the switch control circuit 414 is configured to send a
remote power connection signal 411 indicating the remote power
disconnect state to a remote switch input 413 to open a remote
switch circuit 416 in the remote unit 218 to decouple the remote
unit 218 from power conductor 246+ thereby disconnecting the load
of the remote unit 218 from the power distribution circuit 244.
This allows a measurement current on the power conductors 246+,
246- to be associated with an external load 418 and not the load of
the remote unit 218. When the remote switch circuit 416 is open,
power is provided to the load 401 from the capacitor C.sub.1. The
current measurement circuit 402 measures the current on the power
conductors 246+, 246- while the remote unit 218 is decoupled from
the power source 400. If an external load 418 is not contacting the
power conductors 246+, 246-, this means no current (or only a small
amount of current due to current leakages for example) should flow
from the power source 400 to the power conductors 246+, 246-.
However, if an external load 418, such as a person, is contacting
the power conductors 246+, 246-, this load 418 will present a load
to the power source 400 that will cause current I.sub.2 to flow
from the power source 400 over the power conductors 246+, 246-. Any
measured current I.sub.2 by the current measurement circuit 402 is
communicated to the controller circuit 404. In response to
detection of the external load 418 as a function of the measured
current I.sub.2 exceeding a predefined threshold current level, the
controller circuit 402 is configured to communicate the
distribution power connection control signal 406 indicating a
distribution power disconnect state to the distribution switch
circuit 408 to disconnect the power source 400 from the power
conductors 246+, 246- for safety reasons. This is because the
external load 418 applied to the power conductors 246+, 246- to
cause the current I.sub.2 to flow from the power source 400 may be
a human contacting the power conductors 246+, 246-.
[0044] Note that the management communications link 410 can be a
separate communications link from the power conductors 246+, 246-
or a modulated signal coupled to the power conductors 246+, 246-
such that the remote power connection signal 412 is modulated with
power over the power conductors 246+, 246-. If the management
communications link 410 is provided as a separate communications
link, the management communications link 410 may be electrical
conducting wire, such as copper wires for example. The management
communications link 410 could also carry power to the switch
control circuit 414 to power the switch control circuit 414 since
the management communications link 410 is coupled to the switch
control circuit 414. For example, the predefined current threshold
level may be based on the voltage of the power source 400 and an
estimated 2,000 Ohms resistance of a human. For example, the
International Electric Code (IEC) 60950-21 entitled "Remote
Powering Regulatory Requirements" provides that for a 400 VDC
maximum line-to-line voltage, the human body resistance from hand
to hand is assumed to be 2,000 Ohms resulting in a body current of
200 mA. The remote unit 218 is eventually recoupled to the power
source 400 to once again be operational.
[0045] After the controller circuit 404 communicates the
distribution power connection control signal 406 indicating the
distribution power disconnect state to the distribution switch
circuit 408 to disconnect the power source 400 from the power
conductors 246+, 246-, the controller circuit 404 can be configured
to wait a period of time and/or until a manual reset instruction is
received before recoupling the power source 400 to the remote unit
218. In this regard, the controller circuit 404 can communicate the
distribution power connection control signal 406 indicating a
distribution power connect state to the distribution switch circuit
408 to cause the distribution switch circuit 408 to be closed to
couple the power source 400 to the power conductors 246+, 246-. The
controller circuit 404 can also send the remote power connection
signal 412 indicating a remote power connect state to the switch
control circuit 414 to generate the remote power connection signal
411 to cause the remote switch circuit 416 in the remote unit 218
to be closed to once again couple the remote unit 218 to the power
conductor 246+ thereby connecting the load of the remote unit 218
to the power distribution circuit 244. The capacitor C.sub.1 in the
remote unit 218 is charged by the power source 400 when the remote
unit 218 is coupled to the power conductors 246+, 246-. The energy
stored in the capacitor C.sub.1 allows the remote unit 218 to
continue to be powered during a testing phase when the remote
switch circuit 416 is open. The period of time in which the remote
switch circuit 416 is open is such that the discharge of the energy
stored in the capacitor C.sub.1 is sufficient to power the remote
unit 218. A resistor R.sub.1 is coupled across the remote switch
circuit 416 to allow multiple drops/remote units 218 to be
connected to the same power input 409. The overall equal parallel
resistances can be a higher than the body/touch resistance of
approximately 2 kOhms. The resistance R.sub.1 can be increased by
reducing capacitance C.sub.1 to allow a faster charging time.
Powering the switch control circuit 414 in the remote unit 218 from
the management communications link 410 could avoid the need or
desire to include resistor R.sub.1 as the switch control circuit
414 would be capable of powering on faster and thus also
synchronizing to the power distribution circuit 244(1) faster. With
continuing reference to FIG. 4, note that an optional current
limiter circuit 420 can be provided in the remote unit 218 and
coupled to the remote switch circuit 416. The current limiter
circuit 420 is configured to limit and avoid an in-rush current,
which may be identified by the power distribution circuit 244 as an
overload. This can cause the controller circuit 404 in the power
distribution circuit 244 to send a remote power connection signal
411 indicating the remote power disconnect state to a remote switch
input 413 to open a remote switch circuit 416 in the remote unit
218 to decouple the remote unit 218 from power conductor 246+,
thereby disconnecting the load of the remote unit 218 from the
power distribution circuit 244. A DC/DC converter 421 in the remote
unit 218 can convert a high voltage from the power source 400
(e.g., 400 V) to the required operation voltage of the load 401
(e.g. 48 V). A power line 423 can be provided on the output side of
the DC/DC converter 421 to provide an operational voltage to the
switch control circuit 414 for operation. An optional load switch
circuit 425 can also be provided between the current limiter
circuit 420 and the load 401 to connect and disconnect the load 401
from the power conductors 246+. For example, the load switch
circuit 425 may be under control of the switch control circuit
414.
[0046] In an alternative embodiment, the load switch circuit 425
can be locally controlled by the switch control circuit 414 by a
pulse width modulated (PWM) signal for example instead of being
controlled by the remote power connection signal 412. The PWM rate
is set by the switch control circuit 414 to 0% initially. To switch
control circuit 414 can gradually increase the PWM rate from 0% to
100% to control inrush current. This can also allow the current
limiter circuit 420 to be eliminated, if desired, but elimination
or presence is not required.
[0047] In this example in FIG. 4, a fast distribution power
connection control signal 406 is employed that is implemented at a
lower protocol level for the efficiency of the power transfer, as
it allows shorter load disconnect time, as the power transfer is
done during the load connecting time. A management signal that is
implemented at higher protocol level is subjected to a relatively
high delay variations. In on example, the power connection control
signal 406 is implemented in the physical level only in order to
optimize it to the minimum possible delay variation or jitter. An
improved timing synchronization, between the controller circuit 404
and the load disconnect control may allow a shorter load
disconnecting time needed for the controller circuit 404 to check
for lower current detection. In case of high delay variation, the
disconnect time should be larger in order to ensure additional
margin in order to allow current measurement to be conducted when
there is higher confidence that the load 401 is disconnected. FIG.
5 is a timing diagram 500 illustrating an exemplary timing sequence
502 of the controller circuit 404 in the power distribution circuit
244 in the DCS 200 in FIG. 4 causing the power source 400 to be
coupled to the remote unit 218 for normal operation, and causing
the power source 400 to be decoupled from the remote unit 218 in a
testing operation to detect the external load 418 in contact with
the power conductors 246+, 246-. As shown in FIG. 5, the remote
power connect state and remote power disconnect state of the remote
switch circuit 416 as controlled by the controller circuit 404 is
shown as "CLOSE" states starting at time T.sub.0, T.sub.2, T.sub.4,
T.sub.6, etc. in normal operation phases and "OPEN" states starting
at time T.sub.1. T.sub.3, T.sub.5, T.sub.7, etc. in testing phases.
The period of time between times T.sub.1-T.sub.2, T.sub.3-T.sub.4,
and T.sub.5-T.sub.6 when the remote switch circuit 416 is open is
controlled such that energy stored in the capacitor C.sub.1 when
the remote switch circuit 416 is closed is sufficient to power the
remote unit 218 during the testing phases. The current measurement
circuit 402 measures the current I.sub.2 flowing through the power
conductors 246+, 246- in FIG. 4. To avoid leakage, in one example,
the capacitor C.sub.1 can be charged with a low current when the
remote switch circuit 416 is open, meaning off. Once capacitor
C.sub.1 is charged to a high enough voltage such that the switch
control circuit 414 can identify the remote power connection signal
412, and the remote switch circuit 416 can be turned on and off
periodically as discussed above.
[0048] Between times T.sub.1-T.sub.2, T.sub.3-T.sub.4, and
T.sub.5-T.sub.6, when the remote switch circuit 416 is open
decoupling the remote unit 218 from the power conductors 246+,
246-, the controller circuit 404 detects no current flowing as an
indication that the external load 418 is not contacting the power
conductors 246+, 246-. However, as shown in FIG. 5, after time
T.sub.7, the current measurement circuit 402 measures a current
I.sub.2 which is detected by the controller circuit 404, which is
indicative of the external load 418 being in contact with the power
conductors 246+, 246-. If the controller circuit 404 detects the
current I.sub.2 exceeding the predefined threshold current level,
this indicates the external load 418 being in contact with the
power conductors 246+, 246-. The controller circuit 404 detects the
current I.sub.2 exceeding the predefined threshold current level
shown at 504 in FIG. 5 within the detection time 506. In response,
as shown in FIG. 5, the controller circuit 404 will communicate the
distribution power connection control signal 406 indicating a
distribution power disconnect state to the distribution switch
circuit 408 to cause the distribution switch circuit 408 to be
opened to decouple the power source 400 from the power conductors
246+, 246- for safety reasons.
[0049] Turning back to FIG. 4, the power distribution circuit 244
includes a positive distribution power input 4221(P) configured to
receive current distributed by the power source 400. A negative
distribution power input 4221(N) provides a return path for the
current. The power distribution circuit 244 also includes a
distribution power output 4220 configured to distribute the
received current over the power conductor 246+ coupled to the
remote unit 218. The remote unit 218 coupled to the power
distribution circuit 244 is deemed assigned to the power
distribution circuit 244. The distribution switch circuit 408 is
coupled between the positive distribution power input 4221(P) and
the distribution power output 4220. The distribution switch circuit
408 includes a distribution switch control input 4241 configured to
receive the distribution power connection control signal 406
indicating the distribution power connection mode, which is either
a distribution power connect state or a distribution power
disconnect state. For example, the distribution power connection
mode may be indicated by a bit in the distribution power connection
control signal 406, where a `1` bit is a distribution power connect
state and a `0` bit is a distribution power disconnect state, or
vice versa. The distribution switch circuit 408 is configured to be
closed to couple the positive distribution power input 4221(P) to
the distribution power output 4220 in response to the distribution
power connection mode of the distribution power connection control
signal 406 indicating the distribution power connect state. The
distribution switch circuit 408 is further configured to be opened
to decouple the positive distribution power input 4221(P) from the
distribution power output 4220 in response to the distribution
power connection mode of the distribution power connection control
signal 406 indicating the distribution power disconnect state.
[0050] With continuing reference to FIG. 4, the current measurement
circuit 402 of the power distribution circuit 244 is coupled to the
distribution power output 4220. The current measurement circuit 402
includes a current measurement output 4260. The current measurement
circuit 402 is configured to measure a current at (i.e., flowing
to) the distribution power output 4220 and generate a current
measurement 428 on the current measurement output 4260 based on the
measured current at the distribution power output 4220. The power
distribution circuit 244 also includes a distribution management
communications output 4320 coupled to the management communications
link 410, which is coupled to the assigned remote unit 218. The
controller circuit 404 includes a current measurement input 4341
communicatively coupled to current measurement output 4260 of the
current measurement circuit 402.
[0051] In an alternative embodiment, with reference to FIG. 4, the
need to provide the management communications link 410 between the
controller circuit 404 in the power distribution circuit 244 and
the remote unit 218 to send the remote power connection signal 412
indicating a remote power disconnect state to a switch control
circuit 414 in the remote unit 218 can be avoided if desired. For
example, the remote unit 218 could be configured to cause the
switch control circuit 414 (or the switch control circuit 414
itself could be configured to) periodically open the remote switch
circuit 416 to decouple the remote unit 218 from power conductor
246+ thereby disconnecting the load of the remote unit 218 from the
power distribution circuit 244. The remote unit 218 and/or the
switch control circuit 414 can synchronize to the controller
circuit 404 generating the distribution power connection control
signal 406 to the distribution switch circuit 408 to disconnect the
power source 400 from the power conductors 246+, 246-. For example,
the switch control circuit 414 in the remote unit 218 can be
configured to monitor changes in current I.sub.1 on the power
conductor 246+. The current I.sub.1 will drop each time the
distribution switch circuit 408 disconnects the power source 400
from the power conductors 246+, 246-, thereby disconnecting the
load of the remote unit 218 from the power distribution circuit
244. For example, the controller circuit 404 can be configured to
disconnect the remote unit 218 every 2 ms. The remote switch
circuit 416 can synchronize to this periodic disconnection event in
a short period of time. Thus, if the switch control circuit 414
does not see a current drop on power conductors 246+ within a
predefined period of time when expected according to the expected
periodic disconnect time according to the timing determined by
synchronization process, the switch control circuit 414 can open
the remote switch circuit 416 to decouple the remote unit 218 from
power conductor 246+ thereby disconnecting the load of the remote
unit 218 from the power distribution circuit 244. The switch
control circuit 414 can close the remote switch circuit 416 to
recouple the remote unit 218 to the power conductor 246+ thereby
connecting the load of the remote unit 218 from the power
distribution circuit 244 based on the expected timing of when the
power distribution circuit 244 will close the distribution switch
circuit 408 according to the timing determined by synchronization
process. The discussion of further operation of the power
distribution circuit 244 and the remote unit 218 discussed above
for measuring current on the power conductors 246+, 246- is also
applicable for this embodiment.
[0052] In a second alternative embodiment, to avoid the need to
provide a separate management communications link 410 between the
controller circuit 404 in the power distribution circuit 244, the
controller circuit 404 could be configured to periodically drop the
output voltage on the power conductor 246+ to a known voltage level
(e.g., from 350 VDC to 300 VDC) before communicating the
distribution power connection control signal 406 indicating a
distribution power disconnect state to the distribution switch
circuit 408 to cause the distribution switch circuit 408 to be
opened to decouple the power source 400 from the power conductors
246+, 246-. The remote unit 218 and/or the switch control circuit
414 therein can be configured to monitor the voltage on the power
conductor 246+ to identify this voltage drop as a remote power
connection signal 412 indicating a remote power disconnect state.
In response, the switch control circuit 414 can open the remote
switch circuit 416 to decouple the remote unit 218 from the power
conductor 246+ thereby disconnecting the load 401 of the remote
unit 218 from the power distribution circuit 244. The remote unit
218 and/or the switch control circuit 414 can wait a predefined
period of time to close the remote switch circuit 416 to recouple
the remote unit 218 to the power conductor 246+ thereby connecting
the load 401 of the remote unit 218 from the power distribution
circuit 244 based on the expected timing of when the power
distribution circuit 244 will close the distribution switch circuit
408 according to the timing determined by synchronization process.
The discussion of further operation of the power distribution
circuit 244 and the remote unit 218 discussed above for measuring
current on the power conductors 246+, 246- is also applicable for
this embodiment.
[0053] In a third alternative embodiment, the management
communications link 410 between the controller circuit 404 in the
power distribution circuit 244, the controller circuit 404 could be
configured to periodically drop the output voltage on the power
conductor 246+ to a known voltage level (e.g., from 350 VDC to 300
VDC) before communicating the distribution power connection control
signal 406 indicating a distribution power disconnect state to the
distribution switch circuit 408 to cause the distribution switch
circuit 408 to be opened to decouple the power source 400 from the
power conductors 246+, 246-. The remote unit 218 and/or the switch
control circuit 414 therein can be configured to monitor the
voltage on the power conductor 246+ to identify this voltage drop
as a remote power connection signal 412 indicating a remote power
disconnect state. In response, the switch control circuit 414 can
open the remote switch circuit 416 to decouple the remote unit 218
from the power conductor 246+ thereby disconnecting the load 401 of
the remote unit 218 from the power distribution circuit 244. The
remote unit 218 and/or the switch control circuit 414 can wait a
predefined period of time to close the remote switch circuit 416 to
recouple the remote unit 218 to the power conductor 246+ thereby
connecting the load 401 of the remote unit 218 from the power
distribution circuit 244 based on the expected timing of when the
power distribution circuit 244 will close the distribution switch
circuit 408 according to the timing determined by synchronization
process. The discussion of further operation of the power
distribution circuit 244 and the remote unit 218 discussed above
for measuring current on the power conductors 246+, 246- is also
applicable for this embodiment.
[0054] As shown in the exemplary process 600 in FIG. 6 referencing
the DCS 200 in FIG. 4, in one example option, the controller
circuit 404 is configured to communicate the remote power
connection signal 412 comprising a remote power connection mode
indicating a remote power disconnect state over the distribution
management communications output 4320 coupled to the assigned
remote unit 218 to cause the remote switch circuit 416 to open and
decouple the remote unit 218 from the power conductor 246+ carrying
the current I.sub.1 (block 602 in FIG. 6). The controller circuit
404 is also configured to measure a current I.sub.2 received from
the power source 400 coupled to the power conductor 246+(block 604
in FIG. 6). The controller circuit 404 is configured to determine
if the measured current I.sub.2 on the current measurement input
4341 exceeds a predefined threshold current level (block 606 in
FIG. 6). In response to the measured current I.sub.2 exceeding the
predefined threshold current level indicating that the external
load 418 is contacting the power conductor 246+ or 246-, the
controller circuit 404 is configured to communicate the
distribution power connection control signal 406 comprising the
distribution power connection mode indicating the distribution
power disconnect state to the distribution switch control input
4241 to cause the distribution switch circuit 408 to open to
decouple the power source 400 from the current measurement circuit
402 and the power conductor 246+(block 608 in FIG. 6). For example,
the predefined threshold current level may be less than or equal to
200 mA or less than or equal to 100 mA, as examples. If instead,
the measured current I.sub.2 of the power distribution circuit 244
does not exceed the predefined threshold current level, the
controller circuit 404 is configured to communicate the
distribution power connection control signal 406 to provide the the
distribution power connection mode indicating the distribution
power connect state to the distribution switch control input 4241.
This causes the distribution switch circuit 408 to close or
continue to be closed and couple or continue to couple the power
source 400 to the current measurement circuit 402 and the power
conductor 246+ for providing power to the remote unit 218.
[0055] With continuing reference to FIG. 4, the controller circuit
404 is also configured to communicate the remote power connection
signal 412 comprising the remote power connection mode indicating
the remote power disconnect state over the distribution management
communications output 4320 before determining if the measured
current I.sub.2 on the current measurement input 4341 exceeds a
predefined threshold current level. This causes the remote switch
circuit 416 to open to decouple the remote unit 218 from the power
conductors 246+ or 246-. This is so that when it is desired to test
to determine if the external load 418 is contacting the power
conductors 246+ or 246-, the remote unit 218 is decoupled from the
power conductors 246+ or 246- so that the load 401 of the remote
unit 218 is not causing a current to be drawn from the power source
400. In this manner, any measured current I.sub.2 on the current
measurement input 4341 is an indication of the external load 418
contacting the power conductors 246+ or 246- and not the load 401
of the remote unit 218. As previously discussed, the energy stored
in the capacitor C.sub.1 when the remote unit 218 is coupled to the
power conductors 246+ or 246- allows the remote unit 218 to
continue to be powered during the testing phase when the remote
switch circuit 416 is open.
[0056] With continuing reference to FIG. 4, after the testing
phase, the controller circuit 404 after a predefined period of time
is configured to communicate the remote power connection signal 412
with a remote power connection mode indicating a remote power
connect state over the distribution management communications
output 4320 and over the management communications link 410. This
causes the remote switch circuit 416 to close so that the remote
unit 218 is again coupled to the power conductor 246+ to receive
power from the power distribution circuit 244. The controller
circuit 404 may be configured to communicate the remote power
connection signal 412 with a remote power connection mode
indicating a remote power connect state over the distribution
management communications output 4320 after a predefined period of
time has elapsed communicating the remote power connection signal
412 with a remote power connection mode indicating a remote power
disconnect state. The controller circuit 404 may be configured to
initially communicate the remote power connection signal 412 of the
remote power connection mode indicating the remote power connect
state before communicating the remote power connection signal 412
of the remote power connection mode indicating the remote power
disconnect state, so that the remote unit 218 is initially powered
by the power distribution circuit 244 before any testing phases
begin. As previously discussed in reference to FIG. 5, the
controller circuit 404 may be configured to repeatedly communicate
the remote power connection signal 412 of the remote power
connection mode indicating the remote power connect state during a
normal operation phase, and then communicate the remote power
connection signal 412 of the remote power connection mode
indicating the remote power disconnect state during a testing phase
to continuously detect the external load 418 contacting the power
conductors 246+, 246-.
[0057] FIG. 7 is a graph 700 illustrating exemplary safe and unsafe
regions of body current for a given current impulse time. The graph
700 plots a body current in mA on the X-axis, and a time impulse
exposure duration in ms on the Y-axis. The curve D.sub.1
illustrates a dividing line between a safe region 702 and a danger
region 704 for human contact to a current. The shorter the time
impulse duration of the current, the safer a human can withstand a
larger body current. For example, according to IEC 60947-1, a
current of 200 mA that flows through a human body for less than 10
ms is regarded to be safe and thus plotted in the safe region 702.
Therefore, in one example, power distribution circuit 244 in FIG. 4
is designed in such a way that the close period of the distribution
switch circuit 408 plus the detection time 506 of current
measurement circuit 402 (see FIG. 5) will be lower than 10 ms,
assuming that the time between current detection and the
disconnection of the power supply 400 from the power conductors
246+, 246- by distribution switch circuit 408 is negligible. This
is because the current measurement circuit 402 measured the current
from the connected power source 400 to detect the external load
418, as opposed to detecting the external load 418 through indirect
methods, such as through the discharge of stored energy in
capacitor C.sub.1 that is charged when a power source is connected
and discharges during a testing phase when the power source is
disconnected. In the power distribution circuit 244 in FIG. 4, the
power source 400 is not decoupled from the power conductors 246+,
246- during the testing phase when the current measuring circuit
402 is measuring current I.sub.2. As another example, the power
distribution circuit 244 may be configured to detect a body in
contact with the power conductors 246+, 246- and cause the
distribution switch circuit 408 to be opened in response within
approximately 10 ms or less at a 200 mA body current or less as
shown in area 706 in graph 700. The power distribution circuit 244
may be also configured to detect a body in contact with the power
conductors 246+, 246- within approximately 20 ms or less at a 100
mA body current or less as shown in area 708 in graph 700.
[0058] FIG. 8 is a schematic diagram illustrating the power
distribution system 250 in the exemplary form of the DCS 200 with
the power distribution circuit 244 configured to distribute power
to a plurality of remote units 218(1)-218(X). Common components
between the DCS 200 and the power distribution system 250 in FIG. 4
and FIG. 8 are shown with common element numbers and will not be
re-described. As shown in FIG. 8, a plurality of remote units
218(1)-218(X) are provided. Each remote unit 218(1)-218(X) includes
a remote power input 409(1)-409(X) coupled to the power conductors
246+(1), 246-(1), 246+(X), 246-(X), respectively, which are
configured to be coupled to the power source 400 as previously
described in FIG. 4. The power distribution circuit 244 includes a
plurality of power outputs 8000(1)-8000(X) each configured to
provide power to a respective distribution switch circuit
408(1)-408(X) and current measurement circuit 402(1)-402(X), which
are assigned to different remote units 218(1)-218(X). The current
measurement circuits 402(1)-402(X) are each coupled to a respective
distribution power output 403(1)-403(X) coupled to respective power
conductors 246+(1), 246-(1), 246+(X), 246-(X). Thus, the power
distribution from the power distribution circuit 244 to the remote
units 218(1)-218(X) is in a point-to-multipoint configuration in
this example. The power conductors 246+(1), 246-(1), 246+(X),
246-(X) are also coupled to remote power inputs 409(1)-409(X). The
remote units 218(1)-218(X) may also have remote power outputs
802(1)-802(X) that are configured to carry power from the
respective power conductors 246+(1), 246-(1), 246+(X), 246-(X)
received on the remote power inputs 409(1)-409(X) to an extended
remote unit, such as extended remote unit 218E.
[0059] Also, as shown in the DCS 200 in FIG. 8, the management
communications links 410(1)-410(X) to each of the remote units
218(1)-218(X) are provided by the respective power conductors
246+(1), 246-(1), 246+(X), 246-(X). In this example, a plurality of
controller circuits 404(1)-404(X) are provided and dedicated to
each distribution power output 403(1)-403(X) to control power
distribution for each pair of power conductors 246+(1),
246-(1)-246+(X), 246-(X) through the distribution power outputs
403(1)-403(X) to the remote units 218(1)-218(X). As will be
discussed in more detail below, also in this example, a central
management circuit 804 is provided that is configured to send
multiplexed communications to each of the remote units
218(1)-218(X) to send the remote power connection signal 412
indicating a remote power disconnect state over a respective
management communications link 410(1)-410(X) to decouple the
respective remote unit 218(1)-218(X) to from the respective power
conductor 246+(1)-246+(X) thereby disconnecting the load of the
remote unit 218(1)-218(X) from the power distribution circuit 244
similar to previously described with regard to FIG. 4. Any measured
current I.sub.2 by the respective measurement circuit 402(1)-402(X)
is communicated to the respective controller circuit 404(1)-404(X),
which is in turn communicated to the central management circuit
804. In response to detection of the external load 418 as a
function of the measured current I.sub.2 exceeding a predefined
threshold current level, the central management circuit 804 is
configured to communicate the distribution power connection control
signal 406(1)-406(X) indicating a distribution power disconnect
state to the respective distribution switch circuit 408(1)-408(X)
to disconnect the power source 400 from the respective power
conductors 246+(1)-246+(X), 246-(1), 246-(X) for safety reasons.
Also, as shown in FIG. 8, an extended remote unit 218E may be
coupled to the remote unit 218(1) and also configured to receive
power from the power distribution circuit 244 via the remote unit
218(1).
[0060] FIG. 9 is a schematic diagram illustrating an exemplary
power distribution circuit 244 that can be employed as the DCS 200
in FIG. 8. As shown in FIG. 9, a separate positive side controller
circuit 404P and a negative side controller circuit 404N are
provided. This may provide a lower cost solution than providing a
single controller circuit 404 like in FIG. 4 to control power
distribution to both the power conductors 246+, 246-. The positive
side controller circuit 404P controls the power distribution of
power from the power source 400 provided to the positive
distribution power input 4221(P) to the power conductor 246_. The
negative side controller circuit 404N controls power from the power
source 400 provided to the negative distribution power input
4221(N) to the power conductor 246+. The previous discussion
regarding the features and options of the controller circuit 404
above are applicable to the positive controller circuit 404P and
the negative controller circuit 404N.
[0061] With continuing reference to FIG. 9, the negative controller
circuit 404N is configured to receive first and second current
measurements 428N(A), 428N(B) from first and second current
measurement circuits 402N(A), 402N(B). The negative controller
circuit 404N is configured to communicate distribution power
connection control signals 406N(A), 406N(B) to first and second
distribution switch circuits 408N(A), 408N(B) to control the
coupling and decoupling of the power source 400 to the power
conductor 246- as previously described. The reason for providing
the first and second current measurement circuits 402N(A), 402N(B)
and the first and second distribution switch circuits 408N(A),
408N(B) is for redundancy in the event that one of the first and
second current measurement circuits 402N(A), 402N(B) and/or one of
the first and second distribution switch circuits 408N(A), 408N(B)
fail.
[0062] Similarly, the positive controller circuit 404P is
configured to receive first and second current measurements
428P(A), 428P(B) from first and second current measurement circuits
402P(A), 402P(B). The positive controller circuit 404S is also
configured to communicate distribution power connection control
signals 406P(A), 406P(B) to first and second distribution switch
circuits 408P(A), 408P(B) to control the coupling and decoupling of
the power source 400 to the power conductor 246+ as previously
described. The reason for providing the first and second current
measurement circuits 402P(A), 402P(B) and the first and second
distribution switch circuits 408P(A), 408P(B) is for redundancy in
the event that one of the first and second current measurement
circuits 402P(A), 402P(B) and/or one of the first and second
distribution switch circuits 408P(A), 408P(B) fail. The power
distribution system 250 may service multiple remote units
218(1)-218(X) as illustrated in the DSC 200 in FIG. 8. A
multiplexer circuit 900, which may also be a combiner circuit, may
also be provided as shown in FIG. 9 to multiplex or combine
providing remote power connection signals 412 over the power
conductors 246+, 246-, as previously described.
[0063] With continuing reference to FIG. 9, isolation control lines
902A, 902B are provided between the positive controller circuit
404P and the negative controller circuit 404N. The isolated control
line 902A is used to communicate an immediate alarm signal 904A to
both the positive controller circuit 404P and the negative
controller circuit 404N when there is a need to transfer an
immediate alarm signal 904A to disconnect both the power conductor
246+, 246- due to fault detection, such as an unwanted overload
alarm. Another isolation control line 902B is provided between the
positive controller circuit 404P and the negative controller
circuit 404N. The isolated control line 902B is used as a
management link to carry a management signal 904B from the central
unit 206 to support management functionalities like setting new
current threshold detection levels for example. Examples of current
detection thresholds can include leakage or unwanted load detection
and maximum load/overcurrent detection. Another example of
management functionality is to command the power conductors 246+,
246- to be disconnected to prevent a specific load or user from
receiving power.
[0064] FIG. 10 is a schematic diagram illustrating additional
exemplary detail of additional safety measures that can be provided
for the power distribution circuit 244 of the power distribution
system 250 in FIG. 8. In this example, the controller circuit 404
is configured to periodically generate a watchdog signal 1000. For
example, the controller circuit 404 may generate a watchdog signal
1000 every 1 ms. A watchdog controller 1002 is provided that is
configured to receive the watchdog signal 1000 and provide a
watchdog output signal 1004 in response. The watchdog output signal
1004 is provided to a logic circuit 1006 that is configured to
control the distribution power connection control signal 406. The
logic circuit 1006 is designed so that if the watchdog controller
1002 does not receive the watchdog signal 1000 within a specified
period of time, this means that the controller circuit 404 may have
failed or otherwise may not be operating property. In response, the
watchdog output signal 1004 will be generated to cause the logic
circuit 1006 to provide distribution power connection control
signal 406 in a distribution power disconnect state to cause the
distribution switch circuit 408 to open and decouple the power
supply 400 from the power distribution circuit 244.
[0065] With continuing reference to FIG. 10, if a fault is detected
(e.g., an unwanted overload) such that the power should be
decoupled form the power conductors 246+, 246-, the distribution
power connection control signal 406 indicating the distribution
power connection mode indicating a power disconnection state is
also provided to a status LED 1008. An opto-coupler circuit 1010 is
provided that is configured to detect the power disconnection state
from the status LED 1008 and generate the isolation control signal
904 to the positive controller circuit 404P and the negative
controller circuit 404N. This causes disconnection of power to both
the power conductor 246+, 246- due to this fault detection.
[0066] FIG. 11 is a schematic diagram illustrating another
exemplary, alternative power distribution circuit 244(1) that is
provided in power distribution system 250(1) in the exemplary form
of a DCS 200(1) similar to the DCS 200 in FIGS. 2-3B. The power
distribution circuit 244(1) includes the power source 400 that is
configured to supply power (i.e., current I.sub.1) to be
distributed over the power conductors 246+, 246- to a load 401 of
the remote unit 218 to provide power to the remote unit 218 for
operation of its consuming components like the power distribution
circuit 244 in FIG. 4. Common components between the DCS 200 in
FIG. 4 and the DCS 200(1) in FIG. 11 are shown with common element
numbers therein, and thus will not be re-described. Components
shown in the DCS 200(1) in FIG. 11 shown with a label of `(N)`
operate like their counterpart element numbers without label of
`(N)` in the DCS 200 in FIG. 4.
[0067] In the DCS 200(1) in FIG. 11, the power source 400 is
configured to provide a differential voltage, in the form of a
positive voltage on power conductor 246+, a negative voltage on
power conductor 246-, with a ground conductor 246G. In this
example, this allows an external load 418(1) connected between
power conductors 246+, 246-, an external load 418(2) connected
between power conductors 246+, 246G, an external load 418(3)
connected between power conductors 246-, 246G to be detected by the
power distribution circuit 244(1). To detect an external load
418(3) connected between power conductors 246-, 246G, another
second current measurement circuit 402(N) is provided and coupled
to the power conductor 246-. When non-zero current I.sub.3 is
measured by current measurement circuit 402(N), when remote switch
circuit 416 is open, the controller circuit 404 uses this as an
indication that an external load 418(3) is connected between power
conductors 426- and 426G and directs the distribution switch
circuit 408(N) to be opened.
[0068] The controller circuit 404 may also be configured to compare
the currents I.sub.2, I.sub.3 measured by current measurement
circuits 402, 402(N). If the currents I.sub.2, I.sub.3 are not
substantially identical, the controller circuit 404 may conclude
that current flows through an external load contacting between
either power conductors 246+, 246- to the ground power conductor
ground 426G. In this instance, the controller circuit 404 may cause
distribution switch circuits 408 and 408(N) to both be opened to
decouple the power source 400 from power conductors 246+, 246-.
[0069] Also as shown in FIG. 11, a distribution multiplexer circuit
1100 is provided in the power distribution system 250(1). A remote
multiplexer circuit 1102 is provided in the remote unit 218. For
example, similar to previously discussed in FIG. 8, the
distribution multiplexer circuit 1100 may allow a single controller
circuit 404 (or central management circuit therein as provided in
FIG. 8), to communicate the distribution power connection control
signal 406 to a plurality of remote units 218 one at a time. The
distribution multiplexer circuit 1100 multiplexes the remote unit
218, the distribution power connection control signal 406 is sent.
The multiplexing may be based on frequency-domain multiplexing
(FDM) or time-domain multiplexing (TDM) as non-limiting examples.
The remote multiplexer circuit 1102 can demultiplex the
distribution power connection control signal 406 for
instruction.
[0070] It may also be desired for example, to include a diode
bridge circuit 1104 (e.g., a full bridge diode circuit) coupled to
the power input 409 in the remote unit 218 (e.g., can be part of
the remote multiplexer circuit 1102) to in case the power
distribution circuit 244(1) identifies fault/or unwanted load, and
the controller circuit 404 disconnects distribution switch circuits
408. The diode bridge circuit 1104 can block any potential stored
energy from discharging towards the power conductors 246+, 246-.
Adding a diode bridge circuit 1104 can also make the power input
409 of the remote unit 218 indifferent (i.e., insensitive) to the
polarity of the power conductors 246+, 246- such that the remote
unit 218 can function even if there is a polarity reversal in the
power conductors 246+, 246-. However a drawback may be that for
high current transfer, there is a relatively high power loss in the
diode bridge circuit 1104 (e.g., 5 A on 2 V requires 10 W of heat
dissipation).
[0071] Note that any of the referenced inputs herein can be
provided as input ports or circuits, any of the referenced outputs
herein can be provided as output ports or circuits.
[0072] FIG. 12 is a schematic diagram representation of additional
detail illustrating a computer system 1200 that could be employed
in any component in the DCS 200, including but not limited to the
controller circuits 404 in the power distribution systems 250,
250(1) for coupling a remote unit 218 to the power source 400
during a normal operation phase and instructing the remote unit 218
to decouple from the power source 400 during testing phases to then
measure current from the power source 400 during a testing phase,
including but not limited to the DCS 200 in FIGS. 4, 8 and 11 and
the controller circuits 404, 404M, 404S in FIGS. 4 and 8-11. In
this regard, the computer system 1200 is adapted to execute
instructions from an exemplary computer-readable medium to perform
these and/or any of the functions or processing described
herein.
[0073] In this regard, the computer system 1200 in FIG. 12 may
include a set of instructions that may be executed to program and
configure programmable digital signal processing circuits in a DCS
for supporting scaling of supported communications services. The
computer system 1200 may be connected (e.g., networked) to other
machines in a LAN, an intranet, an extranet, or the Internet. While
only a single device is illustrated, the term "device" shall also
be taken to include any collection of devices that individually or
jointly execute a set (or multiple sets) of instructions to perform
any one or more of the methodologies discussed herein. The computer
system 1200 may be a circuit or circuits included in an electronic
board card, such as, a printed circuit board (PCB), a server, a
personal computer, a desktop computer, a laptop computer, a
personal digital assistant (PDA), a computing pad, a mobile device,
or any other device, and may represent, for example, a server or a
user's computer.
[0074] The exemplary computer system 1200 in this embodiment
includes a processing device or processor 1202, a main memory 1204
(e.g., read-only memory (ROM), flash memory, dynamic random access
memory (DRAM), such as synchronous DRAM (SDRAM), etc.), and a
static memory 1206 (e.g., flash memory, static random access memory
(SRAM), etc.), which may communicate with each other via a data bus
1208. Alternatively, the processor 1202 may be connected to the
main memory 1204 and/or static memory 1206 directly or via some
other connectivity means. The processor 1202 may be a controller,
and the main memory 1204 or static memory 1206 may be any type of
memory.
[0075] The processor 1202 represents one or more general-purpose
processing devices, such as a microprocessor, central processing
unit, or the like. More particularly, the processor 1202 may be a
complex instruction set computing (CISC) microprocessor, a reduced
instruction set computing (RISC) microprocessor, a very long
instruction word (VLIW) microprocessor, a processor implementing
other instruction sets, or other processors implementing a
combination of instruction sets. The processor 1202 is configured
to execute processing logic in instructions for performing the
operations and steps discussed herein.
[0076] The computer system 1200 may further include a network
interface device 1210. The computer system 1200 also may or may not
include an input 1212, configured to receive input and selections
to be communicated to the computer system 1200 when executing
instructions. The computer system 1200 also may or may not include
an output 1214, including but not limited to a display, a video
display unit (e.g., a liquid crystal display (LCD) or a cathode ray
tube (CRT)), an alphanumeric input device (e.g., a keyboard),
and/or a cursor control device (e.g., a mouse).
[0077] The computer system 1200 may or may not include a data
storage device that includes instructions 1216 stored in a
computer-readable medium 1218. The instructions 1216 may also
reside, completely or at least partially, within the main memory
1204 and/or within the processor 1202 during execution thereof by
the computer system 1200, the main memory 1204 and the processor
1202 also constituting computer-readable medium. The instructions
1216 may further be transmitted or received over a network 1220 via
the network interface device 1210.
[0078] While the computer-readable medium 1218 is shown in an
exemplary embodiment to be a single medium, the term
"computer-readable medium" should be taken to include a single
medium or multiple media (e.g., a centralized or distributed
database, and/or associated caches and servers) that store the one
or more sets of instructions. The term "computer-readable medium"
shall also be taken to include any medium that is capable of
storing, encoding, or carrying a set of instructions for execution
by the processing device and that cause the processing device to
perform any one or more of the methodologies of the embodiments
disclosed herein. The term "computer-readable medium" shall
accordingly be taken to include, but not be limited to, solid-state
memories, optical medium, and magnetic medium.
[0079] The embodiments disclosed herein include various steps. The
steps of the embodiments disclosed herein may be formed by hardware
components or may be embodied in machine-executable instructions,
which may be used to cause a general-purpose or special-purpose
processor programmed with the instructions to perform the steps.
Alternatively, the steps may be performed by a combination of
hardware and software.
[0080] The embodiments disclosed herein may be provided as a
computer program product, or software, that may include a
machine-readable medium (or computer-readable medium) having stored
thereon instructions, which may be used to program a computer
system (or other electronic devices) to perform a process according
to the embodiments disclosed herein. A machine-readable medium
includes any mechanism for storing or transmitting information in a
form readable by a machine (e.g., a computer). For example, a
machine-readable medium includes: a machine-readable storage medium
(e.g., ROM, random access memory ("RAM"), a magnetic disk storage
medium, an optical storage medium, flash memory devices, etc.); and
the like.
[0081] Unless specifically stated otherwise and as apparent from
the previous discussion, it is appreciated that throughout the
description, discussions utilizing terms such as "processing,"
"computing," "determining," "displaying," or the like, refer to the
action and processes of a computer system, or similar electronic
computing device, that manipulates and transforms data and memories
represented as physical (electronic) quantities within the computer
system's registers into other data similarly represented as
physical quantities within the computer system memories or
registers or other such information storage, transmission, or
display devices.
[0082] The algorithms and displays presented herein are not
inherently related to any particular computer or other apparatus.
Various systems may be used with programs in accordance with the
teachings herein, or it may prove convenient to construct more
specialized apparatuses to perform the required method steps. The
required structure for a variety of these systems will appear from
the description above. In addition, the embodiments described
herein are not described with reference to any particular
programming language. It will be appreciated that a variety of
programming languages may be used to implement the teachings of the
embodiments as described herein.
[0083] Those of skill in the art will further appreciate that the
various illustrative logical blocks, modules, circuits, and
algorithms described in connection with the embodiments disclosed
herein may be implemented as electronic hardware, instructions
stored in memory or in another computer-readable medium and
executed by a processor or other processing device, or combinations
of both. The components of the distributed antenna systems
described herein may be employed in any circuit, hardware
component, integrated circuit (IC), or IC chip, as examples. Memory
disclosed herein may be any type and size of memory and may be
configured to store any type of information desired. To clearly
illustrate this interchangeability, various illustrative
components, blocks, modules, circuits, and steps have been
described above generally in terms of their functionality. How such
functionality is implemented depends on the particular application,
design choices, and/or design constraints imposed on the overall
system. Skilled artisans may implement the described functionality
in varying ways for each particular application, but such
implementation decisions should not be interpreted as causing a
departure from the scope of the present embodiments.
[0084] The various illustrative logical blocks, modules, and
circuits described in connection with the embodiments disclosed
herein may be implemented or performed with a processor, a Digital
Signal Processor (DSP), an Application Specific Integrated Circuit
(ASIC), a Field Programmable Gate Array (FPGA), or other
programmable logic device, a discrete gate or transistor logic,
discrete hardware components, or any combination thereof designed
to perform the functions described herein. Furthermore, a
controller may be a processor. A processor may be a microprocessor,
but in the alternative, the processor may be any conventional
processor, controller, microcontroller, or state machine. A
processor may also be implemented as a combination of computing
devices (e.g., a combination of a DSP and a microprocessor, a
plurality of microprocessors, one or more microprocessors in
conjunction with a DSP core, or any other such configuration).
[0085] The embodiments disclosed herein may be embodied in hardware
and in instructions that are stored in hardware, and may reside,
for example, in RAM, flash memory, ROM, Electrically Programmable
ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM),
registers, a hard disk, a removable disk, a CD-ROM, or any other
form of computer-readable medium known in the art. An exemplary
storage medium is coupled to the processor such that the processor
can read information from, and write information to, the storage
medium. In the alternative, the storage medium may be integral to
the processor. The processor and the storage medium may reside in
an ASIC. The ASIC may reside in a remote station. In the
alternative, the processor and the storage medium may reside as
discrete components in a remote station, base station, or
server.
[0086] It is also noted that the operational steps described in any
of the exemplary embodiments herein are described to provide
examples and discussion. The operations described may be performed
in numerous different sequences other than the illustrated
sequences. Furthermore, operations described in a single
operational step may actually be performed in a number of different
steps. Additionally, one or more operational steps discussed in the
exemplary embodiments may be combined. Those of skill in the art
will also understand that information and signals may be
represented using any of a variety of technologies and techniques.
For example, data, instructions, commands, information, signals,
bits, symbols, and chips, that may be references throughout the
above description, may be represented by voltages, currents,
electromagnetic waves, magnetic fields, or particles, optical
fields or particles, or any combination thereof.
[0087] Unless otherwise expressly stated, it is in no way intended
that any method set forth herein be construed as requiring that its
steps be performed in a specific order. Accordingly, where a method
claim does not actually recite an order to be followed by its
steps, or it is not otherwise specifically stated in the claims or
descriptions that the steps are to be limited to a specific order,
it is in no way intended that any particular order be inferred.
[0088] It will be apparent to those skilled in the art that various
modifications and variations can be made without departing from the
spirit or scope of the invention. Since modifications,
combinations, sub-combinations and variations of the disclosed
embodiments incorporating the spirit and substance of the invention
may occur to persons skilled in the art, the invention should be
construed to include everything within the scope of the appended
claims and their equivalents.
* * * * *